Electronic Design

EiED Online>> Keeping A Secret

Volume 2004, Number 7

I was originally going to write up an interview with the designers of the Soniqcast Aireo, but they have been a bit busy lately. Instead I'm going to touch upon a common problem with wireless embedded devices like the Aireo. The problem is setting up a secure wireless network. But first a quick overview of what the Aireo is.

Wireless MP3s
I picked up a Soniqcast Aireo (see image) for my daughter's graduation. Since then, there has been a $100 price drop already to $199, but it was worth the cost even at $299. The Aireo has a 1.5-Gbyte hard drive for storing music. That is small for the cost by today's standards, but the inclusion of an 802.11b adapter and synchronization software makes this size more than adequate.

The whole idea is to have a nearby PC with all your MP3s. You create playlists and then specify what amount of hard disk space on the Aireo will be used for a particular mix. The synchronization software, SonicSync, will download only enough music to fill this space. A set of rules covers how additional music will be downloaded at a later time. Some options are to replace music that has been played with music that has yet to be downloaded. The 1.5-Gbyte hard disk will not hold your entire music library, but it will take awhile to listen to all the music it can hold.

In essence, the PC turns into a broadcasting station, and the Aireo is a recorder. The nice part is that download speeds are faster than listening to the music, and the process is essentially automated. Just leave the Aireo in sleep mode overnight, usually while charging it, and SonicSync will do the rest via the 802.11b link. It is also possible to synchronize and configure the Aireo using the USB (universal serial bus) interface.

The Aireo has a few other advantages. It has an FM receiver, and it also incorporates a programmable FM transmitter. Find an unused frequency and tune a nearby FM radio to it; this lets the Aireo transmit its MP3 tunes to the radio. It works nicely with a boom box or car radio. No fancy cables required.

Now back to the problem.

Conflicting Priorities
A wireless laptop is one way to link SonicSync with the Aireo, but I setup an 802.11b wireless gateway instead, because a desktop PC and laptop are destined for the dorm room. By default, most wireless gateways have all security measures disabled. This is definitely a bad thing to have with a thousand inquisitive students at close quarters.

WEP (wireless equivalent privacy) isn't the greatest thing in the world, but it's better than nothing. The first step was to set a 128-bit key using the gateway and Aireo configuration programs. The next trick was to find the MAC (Media Access Control) for the Aireo and enter it in the MAC filter table. All this effort will not guarantee a secure environment, but it will take some effort to get through this and then the firewall on the PC. WPA (Wi-Fi Protected Access) and 802.11g provide better security support, although they still require the same steps to enable security. Use of a VPN (virtual private network) provides even more security, however, this adds yet another step to the configuration process.

The tradeoff is between security versus ease of use and installation. The issue is not unique to consumer applications. In fact, it occurs in industrial and military environments as well.

What's needed is a process similar to the one used to program garage-door openers. The process is simple. Press a button on the door opener, and then press the button on the remote control unit. The door opener remembers the remote control unit. Although this example is a one-way communication process, such remote control units are simply transmitters-the concept for associating a wireless device and a gateway is the same.

If you are building a wireless solution, then security is definitely an issue that will have to be addressed. Even if you have a great product like the Aireo, buyers will be turned off if proper configuration requires a background in networking.

Could Soniqcast improve the installation process? Not really, since it only has control over one end of the system. The security hole exists at the wireless gateway over which they have no control.

Gadget fans will love the Aireo despite the effort necessary to setup a secure wireless network. By the way, the Aireo has an 802.11b hot-spot search function. Let's hope that your wireless network is not sharable by the rest world, unless, or course, that is what you want.


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